Die fob and method of swaging metallic balls



'TNTTED4 STATES PATENT OFFICE.

JOHN B. F. GAY, OF FITCHBURG, MASSACHSETTS, ASSIGNOR TO THE FITCHBIIRG STEEL BALL COMPANY, OF SAME PLACE.

DIE FOR AND METHOD OF SWAGING `lVlETALLIC BALLS.

VSPECIII.`.`IGA'.LIONforming' part of Letters Patent1\[n..11, 5,74, dated September 27, 1898..

Application flied .lingua 1s, 1897. serial No. 648,348. (No model.)

To all whom t may concern:

Be it known that I, JOHN B. F. GAY, a citizen of the United States, residing at Fitchburg, in the county of Worcester and State of Massachusetts, have invented a new and useful Improvement in Dies for and Methods of Swaging Metallic Balls, of which the following is a speciiication, accompanied by drawings, forming a part of the same, in which- Figure 1 represents a plan view of one of the dies. Fig. 2 is a sectional view of the same on line 2 2, Fig. 1. Fig. 3 is a sectional view of thesame on line 3 3, Fig. 1. Fig. 4 represents a central vertical sectional view of a pair of dies with a portion of a rod or bar having a series of balls swaged therefrom and inclosed between the dies. Fig. 5 is an enlarged sectional view of the dies through the center of one of the recesses on line 3 3, Fig. l. Fig. 6 is an enlarged sectional View of `the dies through the center of the series of recesses on line 2 2,-Fig. 1; and Fig. 7 represents a rod with a series of balls partially formed thereon.

Similar letters and reference-figures' refer to similar parts in the different figures.

My invention relates to the dies for and method of swaging metallic balls from rods or bars, and it has for its object to simultaneously swage a series of balls from a single rod or bar; and it consists in subjecting the rod or bar to successive blows between a pair o f peculiarly-shaped dies, whereby a series of circumferential grooves are formed in a rod, dividing it into sections, and each of said sectionsis upset by crowding the metal lengthwise of the rod into spherically-shaped recesses, said rod having been previously selected of a suitable diameter with reference to the distance between said circumferential grooves and less than the required diameter of the swaged ball, so that the metal contained in each section shall be just sufficient to form a ball; and it further consists in providing means for the lateral expansion of the metal in each section of the rod and in rotating the rod relatively to the dies during the operation of swaging in order to bring the swaged rod into circular form at any of its cross-sections.

My invention is particularly designed to swage balls which when ground into absolute sphericity are employed as' friction-balls in the bearings of bicycles and vehicles and in ball-bearings generally. In this class of product it is of the utmost importance that the balls when finished should be true spheres and be of homogeneous texture without flaw and of uniform hardness.

In the manufacture of metallic balls heretofore thel swaging has usually been accomplished by rolling, and when it has been done by hammering two operations with two sets of dies have been required, one for breaking down the rod and the other for shaping the ball, and it has not 4been deemed practicable to swage more than a single ball at each operation, making the manufacture by the process of hammering slow, expensive, and wasteful of material. When the balls are shaped by. the operationfknown as dropforging or by the compression of the metal by a single heavy blow between dies of the desired shape, a projecting fin is formed around the ball which must be cut or ground away, requiring a sepa-rate operation and destroying the homogeneity of the surface of the ball. I have overcome these objections by simultaneously swaging a series of four or more balls at a single operation by means of the swagingdies and the method hereinafter described, whereby the forged balls 'are approximately spherical, of homogeneous texture, and without projecting iins.

In the accompanying drawings, A denotes the upper," and B' the lower, die of a pair of dies by which my invention is carried into practice, said dies being duplicates so far as their working faces are concerned. The lower die B is preferably employed as the stationary die or anvil, and the upper die A is reciprocated by any suitable connected mechanism. `(Not shown.) The dies represented in the accompanying drawings are adapted to swage a series consisting of four balls; but the number can be increased or diminished, if desired, the balls being connected together by a-slender neck which allows the balls to be rotated between the dies and readily separatedl in order to detach them and grind them into true spherical shape. In Fig. 1 I have represented the face or working side of the lower die, the upper die being a duplicate thereof, having four recesses 1 2 3 4. The

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recesses are duplicates, and each consists of an elliptical opening in the face of the die, having its minor axis 5 coincident with the line 2 2, Fig. 1, and corresponding with the diameter of the ball, and its major axis 6 transverse thereto and longer than the di,- ameter of the ball and having the curved bottom 7 preferably spherical, corresponding with the size of the ball to be swaged.

Each division-wall 8 between the recesses is hollowed in the center to afford space for plecks 9, connecting the balls, the edge 10 of e division-wall forming a curved line having a radius much greater than the diameter of the neck 9. The division-walls 8 are beveled between their curved edges 10 and the spherical bottoms 7, as at 11, in order to form a dull edge and make the walls wedge-shaped in their cross-section, as shown at 12 in Figs. 4 and 6.

The outer side walls 13 14 of the outer recesses 1 and 4 are shaped similar to the division-walls 8 by means of recesses l5 16, formed in the sides of the die. The curved bottom 7 of each recess is connected with the ends of the elliptical opening by curved surfaces 17 17, which are preferably tangential to the curved bottom- 7.

In the operation of swaging balls by my improved dies I employ a rod or bar 18 whose diameter is slightly less than the desired diameter of the ball to be swaged. The size of the rod is determined by making it of such diameter that the vmetal contained between the adjacent. edges I() of the dies will be just suflicient to form a ball of the required diameter and a connecting-neck. The rod is inserted between the dies,with its end against a gage 19, which allows the end of the rod to project slightly beyond the side of the die, thereby forming a stub end 2O when the swaging is completed. The first blows of the reciprocating die upon the rod are received by the wedge-shaped walls 12, causing the rod or bar to be upset and the metal to be moved longitudinally toward the center of the recesses and at the lsame time expanded laterally. The rod is turned during the process of hammering, so that the metal which is expanded laterally in a horizontal plane is brought into avertical plane during succeeding blows and is crowded toward the center of the recess.

The operation of swaging a series of balls by means of my improved inventionl is as follows: A rod of the proper size to supply the requisite metal between adjacent edges 10 10 of the dies and having ts diameter slightly less than the required di meter of the ball is inserted between the dies A and B, with the end of the rod projecting slightly beyond the sides of the dies, -as determined by the position of the gage 19. The reciprocating upper die A is then set in motion and the blows de` livered upon the rod are received by the edges l0 of the wedge-shaped walls 12, making dethe recesses, increasing the diameter of the rod, as at 22, Fig. 7, and at the same time expanding the rod laterally, making it oval in cross-section, the continued turning of the rod duringlthe process of swaging reducing its oval cross-section to a circular cross-section and upsetting the rod by crowding the metal against the curved bottom 7 of the recesses. As the curved edges 10 have a much larger radius thanV the diameter of the rod, the lateral expansion of the metal in the necks 9 is received in the spaces 23 at the opposite sides of the rod, and by making the axis 6 of the elliptical opening greater than the axis 5 I provide similar spaces 24 to permit the lateral expansion of the balls 25. If these spaces were not provided, the metal would be expanded between the faces of the dies, producing what is known as a -fin upon the sides of the necks 9 and balls 25, with the liabilityA of forming seams or hammering minute particles of iron into the body of the ball, thereby preventing it from being homogeneous.

The curved bottom 7 shapes the metal as it fills the recess into a globular form sufficiently accurate to enableit to be reduced to a true sphere by the operation of grinding, and the connecting-necks between the balls allow the rod and balls to be turned during the operation of swaging for the purpose of bringing the laterally-expanded metal into a vertical plane, in which it becomes compressed.

I do not conne myself to the specific contour or curvature of the bottom of the recess, so long as the minor axis 5 corresponds approximately with the diameter of the ball and the major axis 6 is longer than the diameter of the ball, whereby each blow of the dies tends to shape the ball into a sphere in central cross-section parallel with the axis of the rod and into an oblate or oval form in cross-section at right angles with the axis of the rod.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. -A pair of dies for simultaneously swaging a series of metallic balls from a rod, each' of said dies having a series of opposing oval recesses inthe vworking faces of 'the dies arranged with .their minoraxes in alinement, each pair of adjacent recesses being separated by a dividing-wall presenting a wedge-shaped edge by which the rod is grooved and upset longitudinally, substantially as described.

2. A pair of dies for simultaneously swaging a series of metallicballs from a rod, each of said dies having a series of opposing oval recesses in the working faces of the dies, arranged with their minor axes in alinement and approximately equal to and with their major axes greater than the diameter of the IOC' IIO

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ball to be swaged to `provide for the lateral expansion of the ball asV it is compressed between the dies, substantially as described.-

3. A pair of dies for simultaneously swag- `ing a series of balls from a rod, each of said A ing a series of metallic balls from a rod, said dies having a series of opposing oval recesses in their working faces, with their minor axes in alinement and approximately equal to the diameter of a ball, with the bottom of each recess semicircular in the cross-section of its minor axes and curved in the cross-section of its major axes, whereby a spherical form is imparted to the ball by the rotation of the rod as it issuccessively compressed by the dies without the formation of a iin, substantially as described.

5. A pair of dies for simultaneously swaging a series of balls from a rod, each of said dies having a series of opposing oval recesses arranged in the working faces of the dies, with their minor axes in alinement and approximately equal to, and with their major axes greater than the diameter of the ball to be swaged, with each: adjacent pair of recesses separated by a wedgeshaped wall slightly hollowed to present a curved edge, shorter-than the major axes of the recesses, said recesses havin g curved bottoms, whereby a spherical shape is imparted to the balls, substantiallyas described.

6. The within-described method of simultaneously swaging a series of balls from a rod, and consisting in swaging a rod of' less diameter than the required diameter of the balls to be swaged between a pair of dies, having a series of opposing oval recesses in their working faces, with their minor axes in alinement and approximately equal to and with their major axes greater, than the requiredV diameter of the swaged ball, said recesses having curved bottoms, with each pair of adjacent recesses in each die separated by a wedge-shaped wall slightly hollowed to form a lenticular space, when the dies are brought together, and rotating said rod a partial revolution between successive blows of the dies, whereby the rod is upset longitudinally by the formation of V-shaped grooves and expanded laterally into spaces provided by' said oval recesses which shape the metal between the wedge-shaped walls into a spherical form, substantiallyas described. v

Dated this'th day of August, 1897.

JOHN B. F. GAY.

Witnesses:

WALTER P. HALL, A. CURRIER. 

